A double-effect LiBr absorption chiller of Hope Deepblue is a high-efficiency absorption refrigeration system that uses the absorption and evaporation properties of a LiBr solution to produce cooling. Unlike single-effect units, double-effect chillers utilize heat sources in two stages with two generators—high-temperature and low-temperature—maximizing energy efficiency. Here is a detailed breakdown of how a double-effect chiller operates:

 

Working Principle of a Double-Effect LiBr Absorption Chiller

 

The double-effect chiller follows an absorption refrigeration cycle that sequentially uses heat energy to create cooling. The cycle uses a two-stage process involving high-temperature and low-temperature generators, allowing for greater thermal energy utilization than single-effect chillers.

 

1. High-Temperature Generator

The high-temperature generator is the system’s main heat input point, typically using steam or hot water at 130-160°C. The concentrated LiBr solution absorbs this heat, causing water to evaporate from the solution, creating high-temperature, high-pressure water vapor. This process lowers the solution concentration, forming a dilute solution.

 

2. Low-Temperature Generator

The high-temperature water vapor is transferred to the low-temperature generator, where it exchanges heat with the dilute solution. This heat further concentrates the solution and produces medium-temperature, medium-pressure vapor.

 

Secondary Evaporation Utilization: The water vapor from the high-temperature generator provides the necessary heat for the low-temperature generator, allowing for additional thermal energy utilization and increasing the system’s total efficiency.

 

3. Condenser

The vapor from the low-temperature generator enters the condenser, where it is condensed into liquid refrigerant by cooling water. The cooling water absorbs the vapor’s heat, and the resulting liquid refrigerant flows to the evaporator.

 

4. Evaporator

In the evaporator, the liquid refrigerant is expanded to a low temperature and pressure, absorbing heat from the surrounding environment to evaporate. This process produces cooling, reducing the temperature of water or air surrounding the evaporator, which is used to cool buildings or industrial equipment.

 

5. Absorber

The water vapor from the evaporator is absorbed by the LiBr solution in the absorber, regenerating the concentrated solution. Heat is released during absorption and carried away by the absorber’s cooling water. The concentrated solution then returns to the high-temperature generator to repeat the cycle.

 

6. Cooling Water Cycle

Cooling water circulates through the condenser and absorber to remove the heat generated in each process, maintaining system operation. The temperature and flow rate of the cooling water significantly impact the chiller’s efficiency.

 

Process Summary

 

The double-effect LiBr chiller achieves high efficiency by utilizing a two-stage heating cycle through its high- and low-temperature generators, maximizing energy utilization. This dual heating approach significantly increases the system’s coefficient of performance (COP), typically 50-80% higher than single-effect chillers, enabling efficient use of heat sources and higher cooling output.

 

Advantages

 

High Efficiency: The dual generator design allows for multiple heat utilization stages, enhancing cooling efficiency.

Energy Savings: Compared to single-effect chillers, double-effect units achieve better energy utilization, reducing energy consumption.

 

Double-effect LiBr absorption chillers are ideal for applications with abundant high-temperature heat sources (e.g., steam or high-temperature water) and are widely used in large buildings, commercial complexes, and industrial cooling systems.